1. Field of the Invention
The present invention relates to telecommunication, and in particular relates to a method of selecting an active SIM for an emergency service and a wireless device utilizing the same.
2. Description of the Related Art
A multi-SIM (subscriber identity module) device, including particularly mobile phones, personal digital assistants, tablet and laptop computers, can hold two or more SIM cards. Each SIM card contains a unique international mobile subscriber identity (IMSI) and the related key which allow a mobile phone user to be identified and authenticated by a service provider. Hereinafter “SIM” and “SIM card” will be used interchangeably. The multi-SIM device allows a mobile phone user to operate with a corresponding number of communication networks and/or arrangements without the need to carry two or more devices, wherein the communication networks may be a Circuit Switched (CS) such as a second Generation (2G) telephony network or a Packet Switched (PS) networks such as an IP Multimedia Subsystem (IMS).
Emergency services include calls to any emergency services agencies, such as police, fire, or ambulance. The emergency calls may be a CS or an IMS call. If the emergency call is bound for a Public Switched Telephone Network (PSTN) number, the PSTN number will be translated into an address of nearest Public Safety Answering Point (PSAP) and the call will be delivered to the address. In IMS, once the call is recognized an emergency it will be routed appropriately without further user checks or authentication procedures.
Since the multi-SIM device contains multiple SIMs, a method of automatic SIM selection for performing emergency services and a multi-SIM device utilizing the same is required.